Contractions of sigma models and integration of massive modes

Abstract

We show how the integration of massive modes after a spontaneous symmetry breaking in a sigma model can often be interpreted as a contraction, induced by a group contraction, of the target space of the sigma model.

9 pages. Prepared for the porceedings of the 4-th International Symposium Quantum Theory and Symmetries. Varna, Bulgaria, 15-21 August 2005